Physicians are required to make many medical decisions ranging from, for example, whether and when a patient is likely to experience a medical condition to how a patient should be treated once the patient has been diagnosed with the condition. Determining an appropriate course of treatment for a patient may increase the patient's chances for, for example, survival and/or recovery. Similarly, predicting the occurrence of an event advantageously allows individuals to plan for the event. For example, predicting whether a patient is likely to experience occurrence (e.g., recurrence) of a disease may allow a physician to recommend an appropriate course of treatment for that patient.
Traditionally, physicians rely heavily on their expertise and training to treat, diagnose and predict the occurrence of medical conditions. For example, pathologists use the Gleason scoring system to evaluate the level of advancement and aggression of prostate cancer, in which cancer is graded based on the appearance of prostate tissue under a microscope as perceived by a physician. Higher Gleason scores are given to samples of prostate tissue that are more undifferentiated [1]. Although Gleason grading is widely considered by pathologists to be reliable, it is a subjective scoring system. Particularly, different pathologists viewing the same tissue samples may make conflicting interpretations.
Conventional tools for assisting physicians in medical diagnostics are limited in scope and application. For example, tools for assisting physicians with decisions regarding prostate cancer treatment after a patient has undergone radical prostatectomy are limited to serum-based PSA screening tests and generalized nomograms. One postoperative nomogram, developed by Kattan et al. U.S. Pat. No. 6,409,664, is widely used by urologists and allows prediction of the 7-year probability of disease recurrence for patients treated by radical prostatectomy. This nomogram provides information about the likelihood of biochemical failure only (i.e., an increase in PSA level), and does not predict clinical failure (death). Moreover, this nomogram only predicts whether a patient's condition is likely to recur within 7 years, and does not predict when in that interval the patient's condition might recur. Prognostic variables used in this nomogram include pre-treatment serum PSA levels, Gleason score, and microscopic assessment by a pathologist of prostate capsular invasion, surgical margins, seminal vesicle invasion, and lymph node status. Treatment failure is recorded when there is clinical evidence of disease recurrence, a rising serum PSA, or initiation of adjuvant therapy. However, these nomograms have several limitations. Of the most notable limitations is that even the best of these nomograms performs only slightly better than mid-way between a model with perfect discrimination (concordance index=1.0) and a model with no discriminating ability (concordance index=0.5). Furthermore, outcome for the approximately 30% of patients who have nomogram predictions in the mid range (7-year progression-free survival, 30-70%) is uncertain as the prediction is no more accurate than a coin toss.
Techniques in computer-implemented image processing and analysis have emerged that provide significantly increased computational power. In many applications, the ability to extract large amounts of quantitative continuous-valued features automatically from a single image has become a reality. A feature X is said to be continuous-valued if, for some A<B, the set of values for the feature includes all numbers x between A and B. Cancer image analysis systems have been developed for images taken from cytological specimens [2] [3]. However, such systems only capture cells and thus do not utilize all of the architectural information observable at the tissue level, let alone combine that information with clinical and molecular information. Cancer image analysis systems have not been provided for analyzing the structure of different pathological elements at the tissue level, which often plays a more important role in diagnosis (e.g., in Gleason analysis) than the appearance of individual cells. Thus, pathologists have resorted to manual techniques for analyzing the shape and size of the prostate gland to determine the pathologic grade of the cancer [4]. The deficiency of conventional cancer image analysis systems is exacerbated by the fact that tissue images are typically more complex than cellular images and require comprehensive domain expert knowledge to be understood.
In view of the foregoing, it would be desirable to provide systems and methods for treating, diagnosing and predicting the occurrence of medical conditions, responses and other medical phenomena with improved predictive power. It would also be desirable to provide computer-implemented systems and methods that utilize information at the tissue level to treat, diagnose and predict the occurrence of medical conditions.